A touch panel device is configured to allow an instrument to receive input of information with a finger or a pen touching a touch panel surface. Capacitance touch panel devices excellent in detection sensitivity as well as in operability have been applied to various instruments in recent years. Among these, projection-type capacitance touch panel devices have often been adopted, which achieve accurate detection of coordinates of a position on a touch panel surface touched by a finger or a pen (see Patent Document 1, for example).
A capacitance touch panel device includes a plurality of drive lines and a plurality of sense lines. The drive lines are each provided with a plurality of X-axis sense electrodes, whereas the sense lines are each provided with a plurality of Y-axis sense electrodes. The capacitance touch panel device is configured to sequentially output drive pulse signals to the drive lines and detect electric field change (capacity change) between the X-axis sense electrodes and the Y-axis sense electrodes. Specifically, the capacitance touch panel device detects, on the sense lines, a signal according to electric field change (capacity change) between the X-axis sense electrode and the Y-axis sense electrode, to detect coordinates of a position on a touch panel surface touched by a finger or a pen.
Such a capacitance touch panel device includes a touch panel having X-axis sense electrodes and Y-axis sense electrodes provided in different layers. The touch panel included in the capacitance touch panel device further includes an insulating layer provided between the layer of the X-axis sense electrodes and the layer of the Y-axis sense electrodes.
The touch panel in the capacitance touch panel device is driven in accordance with drive signals. The sense lines apply predetermined voltage (bias voltage) to cause the Y-axis sense electrodes to have predetermined potential within a predetermined period.
FIG. 11 indicates (exemplary) signal waveforms of a drive signal Tx1 and a sense signal Rx1.
In FIG. 11, the drive signal Tx1 is used to drive, via a first drive line, the X-axis sense electrodes connected to the first drive line. The sense signal Rx1 is used to detect, on the sense lines, a signal according to electric field change (capacity change) between the X-axis sense electrode and the Y-axis sense electrode, and is biased to predetermined potential Vr (e.g. Vr=1.65 [V]) while a predetermined drive line is driven.
A touch panel device is configured generate an electric field on a touch panel surface in accordance with such a drive signal, and includes a receiver configured to receive, via the sense line, a signal (sense signal) according to electric field change caused by touch to the touch panel surface. The tooth panel device is further configured to specify (detect) a touched position on the touch panel surface in accordance with the signal received by the receiver.